With machines for excavation and building works, such as excavating machines, tractors and the like carrying equipment, occasionally the need arises to forcibly rotate the equipment. If the rotation does not for example need to be greater than one quarter of a turn, the rotation can be performed with hydraulic servocylinders which are well known and are suitable force devices for such machines. Occasionally however further rotation is required, up to even a complete turn. This is the case particularly when working in tunnels or on steep slopes or walls, because it may be necessary to excavate or to lever both upwards, downwards and sideways.